1. Field of the Invention
The present invention relates to a method for producing a semiconductor optical device, in particular, to a method for producing a semiconductor optical device including a diffraction grating.
2. Description of the Related Art
Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2008-300737) describes a method for producing a semiconductor device including a diffraction grating. This method includes a step of forming a mask by drawing a pattern for the formation of the diffraction grating. In this step of forming a mask, sections of the pattern constituting a periodic structure are drawn such that the width of their ends in the longitudinal direction is larger than the width of their central portions in the longitudinal direction. As a result, the diffraction grating can be made to have a uniform depth in the entire structure.